Terrestrial radio link is challenged by clear air environmental factors like multipath fading, diffraction fading and atmospheric gaseous losses. These radio link impairments need to be discovered using right meteorological parameters and applying appropriate models so that its result will be used in design of terrestrial radio link of line-of-sight communications. Ethiopia and other countries found in tropical regions are relying on ITU-R database for designing of terrestrial line-of-sight link communication which could end up to over prediction or under prediction of impairments. ITU-R data source was initially prepared from climates of countries located in Temperate region that might not fit for a tropical region. The investigation of finding clear-air radioclimatic parameters for the terrestrial radio-link requires intensive data collection from local meteorological sources. The input parameters to design radio link that comes from investigation depend on local data is expected to be more reliable when it compares to the ITU-R database. Most researchers have used their local data to investigate secondary radioclimatic parameters, that are used as inputs for the design of terrestrial radio-link. But, the meteorological data are limited to their local weather condition, that may not be applied at different geographic locations. This thesis has utilized five to ten years, 15 minutes intervals, surface data of temperature and humidity with one year daily data of Radiosonde were collected from the National Meteorological Agency of Ethiopia. Satellite’s monthly pressure data of "FLDAS Noah Land Surface Model L4 Global" was used and integrated using the Haversine formula with surface data from the meteorological agency to have full information about temperature, pressure, and humidity of selected 58 geographical places in Ethiopia. The Radiosonde data were used for developing a new vertical atmospheric profile model in Addis Ababa. The secondary parameter of the modeled atmospheric profile result was compared with the result of the ITU-R law latitude model and with the ITU-R database. MAE and RMSE are used as the error comparison between the results of the ITU-R results and the proposed model. The performance of the proposed models is found to be better compared to the other models. ArcMap, ExceLab, Ms-Excel, and Python programming are the tools that are used to analyze and demonstrate results in graphs, charts, and maps. This thesis work produces results from the investigation of refractivity, point refractivity gradient, geoclimatic factor K, and k-factor at the selected locations in Ethiopia. The distribution of each parameter is presented in monthly, seasonal, and average year time. The curve fitting approximated for the k-factor distribution is Gaussian normal distribution and the corresponding Integral Square Error approach is used for error checking. The maps and databases are generated using Ordinary-kriging with ArcGIS software tool. The resulting database can be used for consumption by radio link designers.